Coin control is an advanced feature that gives you precise control over which of your bitcoins you spend in a transaction. It's helpful to think of your bitcoin balance not as a single number, but as a collection of different digital "coins" and "notes" you've received in the past. These are technically called Unspent Transaction Outputs (UTXOs). Coin control lets you choose exactly which UTXOs to use, which can significantly improve your financial privacy.
This guide explains what coin control is and how to use it securely with your BitBox02.
Before you begin:
- Please ensure your BitBox02 is fully set up and updated to the latest firmware using the BitBoxApp, and have the device ready to connect and unlock when prompted for secure actions.
- The latest version of Electrum (https://electrum.org) must be installed on your computer.
- You must have already connected your BitBox02 to Electrum. If not, please follow our connection guide (How to connect your BitBox02 with Electrum) first.
The BitBoxApp must be completely closed before you open Electrum, as only one application can connect to the device at a time.
Step-by-step guide to using coin control:
Coin control allows you to choose which specific pieces of bitcoin (UTXOs) you want to spend in a transaction. This is an advanced feature that can help you manage your privacy and optimize transaction fees.
- To enable this feature, go to the menu and select View > Show Coins.
- A new Coins tab will appear. Switch to this tab to see all the individual UTXOs in your wallet.
- Select the specific UTXOs you want to spend.
- Right-click on your selection and choose Add to coin control.
- A 'coin control active' message will appear at the bottom of the window.
- Now, when you go to the 'Send' tab to create a transaction, Electrum will only use the coins you have selected.
You can find a detailed guide on this topic in the official Electrum documentation How to spend specific UTXOs in Electrum
FAQ Section:
Why is coin control important for privacy?
When you spend multiple UTXOs in a single transaction, you create a permanent link between them on the public blockchain. If one of those UTXOs can be traced back to you (for example, from a crypto exchange), then all other UTXOs in that transaction can also be linked to you. Coin control allows you to avoid mixing UTXOs from different sources.
What does it mean to 'freeze' a coin?
Freezing a coin in the 'Coins' tab tells Electrum not to include it when automatically creating transactions. This is useful if you want to hold onto a specific UTXO, perhaps for privacy reasons or because it has a unique history (e.g., it was a gift).
Can using coin control affect my transaction fees?
Yes. Transaction fees are based on the data size of a transaction. A transaction with many inputs (UTXOs) will be larger and therefore cost more in fees than a transaction with just one or two inputs. Coin control can help you manage fees by allowing you to choose which UTXOs to spend.